(To be removed) Read data from SDTS raster/DEM data set
[Z, R] = sdtsdemread(filename)
[Z, R] = sdtsdemread(filename) reads
data from an SDTS DEM data set.
Z is a matrix containing
the elevation values.
R is a referencing matrix.
NaNs are assigned to elements of
Z corresponding to null data values or fill data
values in the cell module.
filename can be the name of the SDTS catalog directory file
*CATD.DDF) or the name of any of the other files
in the data set.
filename can include the directory name;
filename is searched for in the current
directory and the MATLAB® path. If any of the files specified in the catalog directory
[Z, R] = sdtsdemread('9129CATD.ddf'); mapshow(Z,R,'DisplayType','contour')
Elevation values can be imported with
sdtsdemread from DEMs
that use the SPRE Raster Profile (in use since January, 2001) as well as
from older SDTS DEM data sets. Under this profile, elevations can be encoded
either as 32-bit floating-point numbers (when their units are
“decimal meters”), or as 16-bit integers (when units are
“feet” or “meters”). The output class from
sdtsdemread for both types of elevation encoding is
For details on locating map data for download over the Internet, see the following documentation at the MathWorks Web site: Find Geospatial Data Online.
sdtsdemreadwill be removed
Not recommended starting in R2020a
Raster reading functions that return referencing matrices will be
sdtsdemread. Instead, use
readgeoraster, which returns a raster reference
object. Reference objects have several advantages over referencing
Unlike referencing matrices, reference objects have
properties that document the size of the associated
raster, its limits, and the direction of its rows
and columns. For examples of reference object
Most functions that accept referencing vectors as input also accept reference objects.
To update your code, change instances of the function name
readgeoraster and specify an extension
for the data file. The
returns data using the native data type embedded in the file. Return
a different data type by specifying the
[Z,R] = readgeoraster('9129CATD.ddf','OutputType','double');
readgeoraster function does not automatically
replace missing data with
NaN values. If your
data set uses large negative numbers to indicate missing data,
replace them with
NaN values using the
[Z,R] = readgeoraster('9129CATD.ddf'); info = georasterinfo('9129CATD.ddf'); m = info.MissingDataIndicator; Z = standardizeMissing(Z,m);